My question is : I want to know when does a xLayout (or ViewGroup in general) add a child view from XML ? And by "when" I mean at what point of code, in what "pass" of the "traversal" of the UI toolkit ? Which method of xLayout or ViewGroup should I override ? I have done my homework : I have watched the "Writing Custom Views For Android" presented (by Adam Powell and Romain Guy) in the last Google I/O and I have read Adam Powell comments on this Google+ post.